Developing a High-Temperature Solvent-Free System for Efficient Biosynthesis of Octyl Ferulate

Abstract

Ferulic acid esters have been suggested as a group of natural chemicals with sunscreen function. The study aimed to utilize an environment-friendly enzymatic method to produce octyl ferulate by esterification of ferulic acid with octanol. The Box-Behnken design with response surface methodology (RSM) was adopted to evaluate the effects of synthesis variables, including reaction temperature (70-90 °C), enzyme amount (1,000-2,000 PLU) and stir speed (50-150 rpm), on the molar conversion of octyl ferulate. According to the joint test, both the reaction temperature and enzyme amount had great impacts on the molar conversion. RSM-developed second-order polynomial equation further showed great ability on data-fitting. Based on ridge max analysis, the optimum parameters for the biocatalyzed reaction were: 72 h reaction time, 92.2 °C reaction temperature, 1,831 PLU enzyme amount and 92.4 rpm stir speed, respectively. Finally, the molar conversion of octyl ferulate under optimum condition was verified to be 93.2 ± 1.5%. In conclusion, high yield of octyl ferulate synthesized by commercial immobilized lipase under elevated temperature conditions has been suggested, which our findings could broaden the utilization of the lipase and provide a biocatalytic approach, instead of the chemical method, for ferulic acid ester synthesis.